Construction of the border wall prototypes as seen Oct. 17, 2017, near the Otay Mesa Port of Entry outside San Diego. President Trump travels to San Diego to look at the eight prototypes Tuesday, March 13, 2018.

David Wallace, The Arizona Republic

SAN DIEGO — President Trump on Tuesday stood alongside the prototypes of the wall on the U.S. border with Mexico, the first tangible steps towards fulfilling one of his most popular and persistent campaign promises.

“If you don’t have a wall system, we’re not going to have a country,” Trump said in brief remarks during his tour.

Trump toured the eight prototypes alongside Rodney Scott, the chief Border Patrol agent for the San Diego sector and James O’Loughlin, the project manager. O'Loughlin carried a three-ring binder with information for the president about the prototypes. Scott showed Trump pictures of the area before and after the current fencing went up, showing how those restored "law and order" to the region.

Trump said he preferred a wall design that allowed Border Patrol agents to see through the barrier.

“You have to know what is on the other side of the wall,” he said. “You can be two feet away from a criminal cartel and you don’t even know that they are there.”

Trump said he also preferred the taller walls, saying they acted as a deterrent to people crossing illegally, whom he compared to "professional mountain climbers."

Trump said he noticed while driving to the prototypes, along the eastern suburbs of San Diego, that the existing border fence was filled with holes that were patched over. “It’s not doing the trick because they cut holes in it,” Trump said. “The fence is not strong enough. It’s not the right idea.”

In a news conference following his tour, Trump used a bit of Spanish to discuss picking the best design. "We want to make it perfecto," he said.

Prepping the border for Trump

On Monday, U.S. Customs and Border Protection spruced up the area around the structures in time for Trump’s photo opp with the prototypes. Workers added gravel to the dirt roads leading to the site to make it easier to reach, and around the prototypes to make it easier to walk among them. They also propped up metal shipping containers on the south side of the prototypes to block the view from the Mexican side of the border.

Mexican police announced they also would secure the area south of the border. They restricted access to the Mexican side of the prototypes for the duration of Trump’s visit, police said.

On Tuesday morning, Mexican federal police cordoned off approximately three blocks of the dirt road that runs along the existing border wall. Just behind the wall, which is painted with murals featuring pro-migrant and peaceful messages, the eight border wall prototypes tower, visible from the Tijuana side.

The neighborhood near this section of the border wall is industrial. About three dozen federal police were patrolling the area. Reporters from local and national outlets climbed onto roofs of homes and businesses to get a bird's eye view of the prototypes.

The prototypes sit about 100 feet from the solid metal fencing that separates both countries.

On the Tijuana side, two men held up a sign that read, in Spanish, "Parks not walls."

Daniel Watman said that instead of a wall, he envisioned an open park similar to the Peach Arch Park at the U.S. border with Canada in western Washington state.

President Donald Trump visits California on March 13, 2018

A crowd of protesters gather at the San Isidro Border in San Diego Calif., to protest during President Trump's visit to see border wall prototypes on Tuesday, March 13, 2018.

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A crowd of protesters gather at the San Isidro Border in San Diego Calif., to protest during President Trump's visit to see border wall prototypes on Tuesday, March 13, 2018.

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“The separation results in people not getting to know each other,” said Watman, a U.S. citizen who now lives in Tijuana.

On the U.S. side, even though the 30-foot structures tower over the containers, the boxes effectively block direct views of the ground north of the prototypes, where Trump was to observe them.

President Donald Trump delivers remarks at the Make America Great Again Rally on March 10, 2018, in Moon Township, Pa. Trump heads to California on Tuesday, March 13, 2018, where he will view the border wall prototypes.

Nicholas Kamm, AFP/Getty Images

"We can, obviously, expect him to talk about the wall itself and how it looks," said John J. "Jack" Pitney Jr., a political scientist at Claremont McKenna College in Southern California. "What will be interesting is to hear how much he says about California. How much is he going to attack the state?"

Pitney joked that Trump "is making friends with North Korea and declaring war on California," referring to Trump's seeming openness to participating in a high-stake nuclear summit with the rogue nation.

"Immigration is the biggest substantive issue (of disagreement), but he has lots of problems with lots of the state's politicians, including Nancy Pelosi and Maxine Waters," Pitney said.

Waters, a Democratic congresswoman from Los Angeles, has called for Trump's impeachment; in turn, Trump on two recent occasions has taken shots at Waters, insulting her IQ.

"Obviously, demonstrators will be kept far away but we'll see how many of them turn out and how loud they are."

Trump's first visit to California met with opposition, support

The trip is Trump's first to California as president and, given his seemingly irreconcilable differences with the state's prevailing political culture, he is expected to be met by demonstrators. Several groups have already announced anti-Trump events, such as Nuevo Movimento's protest march planned for Otay Mesa, Calif.

“The main message is to get it through Trump’s head that he’s not welcome in San Diego or California, period,” organizer Jenerai Del Castillo previously told the USA TODAY Network.

Roundup of border wall protest art

Murals in Tijuana, Mexico, across the border from prototypes of President Trump's border wall, are shown on March 12, 2018.

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Murals in Tijuana, Mexico, across the border from prototypes of President Trump's border wall, are shown on March 12, 2018.

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At least one group, San Diegans for Secure Borders, organized a pro-Trump rally.

A group of about 200 people gathered in Otay Mesa, waving flags and signs.

Arthur Shaper of Torrence, Calif., held a bullhorn and led some chants. A sample: "Build that wall, nice and tall. Round them up and deport them all."

Shaper said he voted for Trump because of his promise to build the wall on the border.

"We've got to stop the drug flow," he said. "We've got to stop the gang flow and the human trafficking."

Near the border wall prototypes Tuesday, several Trump supporters gathered on a corner behind a police barricade, waiting for his arrival. As a car passed, a man shouted from the window: "USA, USA!"

Near the San Ysidro border crossing, a crowd of about 75 pro-migrant protesters chanted: "No hate, no fear. Immigrants are welcome here."

Jules Luna, who lives in Westminster, Calif., in Orange County, wore a black beret, raised a fist and joined in the chants.

"I don't really have any words to (the) absurdity of the building a wall," said Luna. "It's really just a monument to (Trump's) ego and hatred and racism. It's a senseless wall."

Both rallies broke up shortly after Trump landed.

Trump clashes with California's politicians

Trump's border visit marked his first trek to California, a deep-blue state that overwhelmingly voted for his Democratic rival Hillary Clinton in the 2016 election and is being sued by his Justice Department over "sanctuary" immigration laws.

On Monday, the Trump administration pushed back against House Minority Leader Nancy Pelosi for suggesting that immigration authorities "terrorize" families with "unjust and cruel raids."

"Our ICE officers are protecting the immigrant community," Homan told reporters on a conference call. "You’re talking about law enforcement people that get up every day and leave the safety and security of their home, strap on a gun ... to defend this nation.”

Homan also complained that California law prohibits ICE from picking up people from state and local jails.

"We should get access to all their criminals," he said.

The Justice Department earlier this month sued California over three state "sanctuary state" statutes. The laws ban employers and law-enforcement officials from cooperating with federal immigration authorities and provide for a state review of federal immigration detention, which the Justice Department says amounts to California unlawfully trying "to regulate the federal government."

California Gov. Jerry Brown responded to the U.S. lawsuit by accusing U.S. Attorney General Jeff Sessions of using "political stunts" to "further divide and polarize America."

After speaking at Marine Corps Air Station Miramar, Trump was expected to headline a fundraiser in Beverly Hills to benefit "Trump Victory," a joint fundraising committee benefiting his presidential campaign and the Republican National Committee.

Border wall prototypes

Three border wall prototypes are seen among the construction of the prototypes near the Otay Mesa Port of Entry outside of San Diego, California, as seen from behind the pre-existing border fencing on the international border between the U.S. and Tijuana, Mexico, on Oct. 16, 2017.

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Three border wall prototypes are seen among the construction of the prototypes near the Otay Mesa Port of Entry outside of San Diego, California, as seen from behind the pre-existing border fencing on the international border between the U.S. and Tijuana, Mexico, on Oct. 16, 2017.